Convert player-typed sentences to game/world commands

[oubiwann]

Tasks:

• Add the ability to parse user-provided text - Add the ability to parse user-provided text #32
• Support command synonyms - Identify command synonyms and standardize phrasing internally #34
  • Identify command synonyms
  • Standardize phrasing internally
• Devise data structure (AST) for the parsed results of user-supplied commands - Devise data structure (AST) for the parsed results of user-supplied commands #37